1. Field of the Invention
The present invention relates to stepwisely variable automatic transmissions of motor vehicles, and more particularly to the stepwisely variable automatic transmissions of a type that exhibits a reduced friction loss at each speed established.
2. Description of the Related Art
Japanese Laid-open Patent Application (Tokkai) 2001-182785 shows a stepwisely variable automatic transmission that establishes eight forward speeds and two reverse speeds by operating three planetary gear units and six frictional elements in a controlled manner. The three planetary gear units are a double pinion type planetary gear unit, a Ravigneaux-double pinion type planetary gear unit and a Ravigneaux-single pinion type planetary gear unit, and the six frictional elements are four clutches and two brakes.